The present invention relates generally to voltage controlled oscillators (VCO's). An inductively coupled oscillator is disclosed.
VCO's are commonly used in communication systems, as well as other applications. Multiple oscillators may be cascaded in a ring to improve noise and performance and may be configured with various different phase relationships among the oscillators in the cascade. Kim, which was previously incorporated by reference, discloses a VCO that includes multiple oscillators configured to oscillate synchronously, in phase with each other. The oscillators are electrically coupled to cause the synchronous oscillation. Because the oscillators oscillate in phase, it is possible to arrange the inductors that are included in the oscillators so that the inductors are mutually inductive.
One of the ways that noise is introduced into a cascaded oscillator is through the wires and switches that comprise the electrical connections between oscillators that couple the oscillators and cause synchronous oscillation. It would be useful if such noise could be reduced. Furthermore, it would be useful if improved coupling schemes for synchronous oscillator cascades could be developed and if improved inductor layout schemes could be developed for inductors configured to be mutually inductive.